Damping means for ultrasonic transmitters

ABSTRACT

There is disclosed an ultrasonic transmitter employing a rod adapted to be mechanically vibrated in a longitudinal mode. The rod is struck at one end by a hammer assembly and is restrained at the opposite end to damp vibrations of the rod by a spring damper means mounted on the transmitter housing.

United States Patent 1 Lazzery 1 1 DAMPING MEANS FOR ULTRASONIC TRANSMITTERS [75] Inventor: Angelo Gino Lazzery, Oaklyn, NJ. [73] Assignee: RCA Corporation, New York, NY.

[22] Filed: Oct. 4, 1971 [21] Appl. No.: 186,167

[52] US. Cl. 116/137 A, 84/404 [51] Int. Cl B06b 3/00 [58] Field of Search 116/137, 137 A, 149, 116/169; 84/404-410 [56] References Cited 7 UNITED STATES PATENTS 890,341 6/1908 Deagan 116/169 1,490,476 4/1924 Morris 84/407 Dec. 11, 1973 2,728,902 12/1955 White 84/404 X 2,920,604 1/1960 McDona1d,.1r... 116/137 A 3,017,849 1/1962 Grossenheider. 116/137 A 3,048,144 8/1962 Vistain, Jr 116/137 A 3,068,834 12/1962 Kemeny 116/137 A 3,165,090 1/1965 Smith 116/137 A Primary Examiner-Louis J. Capozi Attorney-Eugene M. Whitacre [57 ABSTRACT 6 Claims, 1 Drawing Figure PMENIEBDEC n ma 3.777;"!00

INVENTUR. KIA/sew Gmo Ln zzenv OMf-( w ATTORNEY DAMPING MEANS FOR ULTRASONIC TRANSMITTERS This invention relates to an ultrasonic transmitter and, more particularly, to such a transmitter using a longitudinal mode mechanical resonator to generate a signal in the ultrasonic region.

Ultrasonic signals have been widely utilized in the prior art for remote control purposes. Such ultrasonic units as transmitting and receiving systems are utilized to control television sets, garage doors and for other purposes as well.

A device for generating such signals is an elongated metal rod proportioned to generate signals in the ultrasonic range. In such devices mechanical energy is usually delivered to the end of the rod by means ofa hammer moving along the longitudinal axis of the rod. This energy serves to excite the rod causing longitudinal vibrations to occur at a frequency determined by the physical length of the resonator and the propagation velocityof sound in the material from which the resonator is formed.

It is well known that when energy is imparted to such a rod, the vibrations emitted have an initial peak amplitude which decays exponentially with time. In order to prevent spurious operation of the ultrasonic receivers, it is desired to prevent the resonator from false operation and to assure that the resonator ceases to vibrate when the user of the ultrasonic transmitter releases the actuator. v

The prior art contains a number of techniques which function to restrain the rod from vibrating after a predetermined duration by damping the rod by means of a mechanical assembly which coacts with the side of the rod. Certain of these devices are relatively complicated in structure and are difficult to implement.

It has been known that an alternate and more efficient way to damp the rod would be to restrain the same by means coupled to the end of the rod instead of the side. These means would serve to hold the rod at its end to prevent the same from vibrating after a predetermined duration.

In accordance with the present invention, an elongated longitudinal mode vibrator is mounted on a support member which is mounted on a housing. The vibrator has a resonant frequency within the ultrasonic band. A striking element is operatively associated with one end of the vibrator to excite the vibrator into mechanical oscillations and a damping element mounted on the housing is operatively associated with the other end of said vibrator. Means for controlling said damping element are responsive to the return of an actuator to an initial position after said' striking element excites said vibrator to damp said oscillations by coacting with said other end of said vibrator.

The sole FIGURE is a cross-sectional side view of an ultrasonic transmitter employing a damping mechanism according to this invention.

Referring to the FIGURE, an ultrasonic transmitter assembly is mounted in a housing 11 of suitable dimensions enabling the same to be easily accommodated as a hand-held unit by a user. The housing 11 has a screen 12 on one end thereof to allow the free propagation of ultrasonic waves.

An aluminum rod 15 which has an annular groove 17 is supported by a spring support member 16, which snaps into the groove 17. The groove 17 is located near the center of the rod, at a nodal point for longitudinal vibrations so that the support member 16 has minimum damping effect upon the vibration of the rod. A generally cylindrical hammer 18 has a central aperture for slideable mounting on a bar 19. Bar 19 is rigidly secured to one end of the housing 11. A helical spring 20, which is coaxial with the bar 19 is fastened at one end to the hammer and at its other end to the housing 11. A manually operable actuator 22 is slideably mounted on the top surface of the housing 11. The actuator 22 is affixed to a slideable bar 23 by an upstanding tab 24, which may be an integral part of the bar 23. The bar 23 has a downwardly extending tab 30 which is coupled by means of a return spring 25 to a pin 26 on the top cover of the housing 11.

The end of the bar 23 which is closest to the hammer portion of the assembly has a rotatable trigger member 27 at one end. The member 27 has one end thereof adapted to coact with a flange 21 on the hammer l8, and is biased in the position shown by a spring member, 31. The opposite end of the bar 23 is curved downwardly to form an end flange 28.

A metallic spring member 29 of general arcuate configuration is secured at one end to a post 32 mounted on the bottom wall of the housing. The free end of the spring is biased away from the end of the rod 15, but will be pushed into engagement therewith when engaged by the flange 28.

In operation, when the actuator 22 is moved towards the right, the spring 25 is stretched. The trigger 27 engages the flange 21 and this causes the hammer 18 to move to the right to compress the spring 20. Because the rod 19 is at an angle with respect to the slide bar 23, a point is reached where the trigger 27 can no longer contact the flange 21. At this point the hammer slips past the trigger, and the stored energy in the spring 20 drives the hammer 18 to strike the sonic rod 15.

During the above-described operation, the rod 15 is not damped because the movement of the actuator 22 to the right causes the flanged end 28 of bar 23 to be withdrawn from the spring element 29. This causes the spring member 29 to move towards the dashed line position shown in the drawings, and hence the spring element 29 no longer contacts or restrains the end of the bar 15.

Thus when the actuator is released, the bar continues to vibrate for a predetermined duration. This duration is determined by the action of the spring 25 in returning the bar 23 to its initial position as shown in the F IG- URE.

When the operator releases the actuator 22, the spring 25 returns it to the rest position shown in the FIGURE.

Thus the following sequence occurs. As the actuator 22 is moved towards the right, the spring member 29 is retracted from the end of the sonic rod 15. At a predetermined position (dashed line) the hammer 18 is released and is returned by the spring 20 to impact the associated end of the rod 15. The rod 15 vibrates until the actuator is released and spring member 25 returns the bar 23 to the position shown, at which time the flanged end 28 of the bar 23 forces the arcuate spring 29 back to the position shown, thus restraining the rod 15 from vibration.

In this manner, damping of the rod is reliably accomplished at the end of the rod resulting in increased efficiency over prior art side damping techniques. It is noted that the metallic spring damping element 29 is the only additional part necessary to implement prior art ultrasonic generators of the type shown in the FIG- URE to thereby afford reliable damping techniques.

What is claimed is:

1. An ultrasonic wave transmitter comprising:

a housing,

an elongated rod responsive to the striking of one end thereof to generate ultrasonic waves,

means supporting said rod near the center thereof,

mounted on said housing,

a hammer,

mounting means including a spring member for supporting said hammer adjacent said one end of said rod,

a damping member rigidly secured to said housing near the other end of said rod and having a first position engaging said other end of said rod for damping vibrations therein and a second position spaced from said other end of said rod,

actuator means slideably movable from a first position to a second position to tension said spring member and cause said hammer to strike said one end of said rod, said actuator means coupled to said damping member to cause said damping member to assume the first position and to assume the second position when said actuator means is slid to its second position.

2. In combination with an elongated longitudinal mode vibrator mounted on a support member and having a resonant frequency within the ultrasonic band, a housing, a striking element operatively associated with one end of said vibrator to excite said vibrator into mechanical oscillations at said frequency, a damping element rigidly secured to said housing and operatively associated with said other end of said vibrator, and a slideable actuator for controlling said damping element to damp said oscillations by coacting with only said other end of said vibrator.

3. The combination according to claim 2 wherein said damping element comprises:

a spring member having at one end of an arcuate configuration contiguous with another relatively flat end, said flat end rigidly secured to said housing and said spring member positioned with said arcuate end coacting with said other end of said vibrator.

4. In combination with an elongated longitudinal mode vibrator mounted on a support member and having a resonant frequency within the ultrasonic band:

a housing,

manually operable actuator means slideably mounted on said housing and having a first end and a second end,

a striking element coupled to said actuator means at said first end and mounted on said housing and positioned with respect to an end of said vibrator to mechanically strike said vibrator in response to the operation of said manually operable actuator, and

an arcuate damping spring member engaging said manually operable actuator means at said second end and rigidly secured to said housing and positioned with respect to another end of said vibrator to coact with said vibrator at said other end in a first nonoperating position of said manually operable means and to move away from said other end when said actuator is slideably operated.

5. An ultrasonic transmitter comprising:

a housing,

support means, mounted on said housing,

an elongated rod mounted on said support means and adapted to resonate within said ultrasonic band upon being mechanically excited,

an actuator mechanism slideably mounted on said housing and having a first flanged end and a second end,

a striking mechanism including a spring moveably mounted with respect to said housing and positioned at one end of said rod, said striking mechanism being coupled to said second end of said actuator mechanism to compress said spring when said actuator is caused to slide towards said striking mechanism, said compressed spring providing energy to cause a striking member to impinge upon said rod and therefore mechanically excite the same,

a damping spring member of an arcuate shape and having a first end rigidly secured to said housing, said damping spring member coacting with said flanged end of said actuator member during a first position to cause said other end of said spring member to coact with the other end of said rod to restrain vibration and to move from said end to a second position, when said actuator slides towards said striking mechanism, to enable vibration.

6. A manually powered ultrasonic signal transmitter comprising:

a housing,

a support member mounted on said housing,

an elongated longitudinal mode mechanical vibrator having a predetermined natural ultrasonic frequency,

means for mounting said vibrator on said support member,

manually operable motion transmitting means mounted on said housing in a manner which provides for a sliding motion of the manually operable motion transmitting means,

a striking element coupled to said motion transmitting means and responsive to the operation thereof to move against an end of said vibrator and to strike said vibrator to cause the same to mechanically vibrate at said predetermined frequency, and

an arcuate spring damping element rigidly secured to said housing and coupled to said manually operable motion transmitting means, said arcuate spring member positioned to coact with another end of said vibrator to restrain vibrations when said manually operable means are not operated and to move away from said other end in response to a sliding motion of said manually operable means to permit vibrations. 

1. An ultrasonic wave transmitter comprising: a housing, an elongated rod responsive to the striking of one end thereof to generate ultrasOnic waves, means supporting said rod near the center thereof, mounted on said housing, a hammer, mounting means including a spring member for supporting said hammer adjacent said one end of said rod, a damping member rigidly secured to said housing near the other end of said rod and having a first position engaging said other end of said rod for damping vibrations therein and a second position spaced from said other end of said rod, actuator means slideably movable from a first position to a second position to tension said spring member and cause said hammer to strike said one end of said rod, said actuator means coupled to said damping member to cause said damping member to assume the first position and to assume the second position when said actuator means is slid to its second position.
 2. In combination with an elongated longitudinal mode vibrator mounted on a support member and having a resonant frequency within the ultrasonic band, a housing, a striking element operatively associated with one end of said vibrator to excite said vibrator into mechanical oscillations at said frequency, a damping element rigidly secured to said housing and operatively associated with said other end of said vibrator, and a slideable actuator for controlling said damping element to damp said oscillations by coacting with only said other end of said vibrator.
 3. The combination according to claim 2 wherein said damping element comprises: a spring member having at one end of an arcuate configuration contiguous with another relatively flat end, said flat end rigidly secured to said housing and said spring member positioned with said arcuate end coacting with said other end of said vibrator.
 4. In combination with an elongated longitudinal mode vibrator mounted on a support member and having a resonant frequency within the ultrasonic band: a housing, manually operable actuator means slideably mounted on said housing and having a first end and a second end, a striking element coupled to said actuator means at said first end and mounted on said housing and positioned with respect to an end of said vibrator to mechanically strike said vibrator in response to the operation of said manually operable actuator, and an arcuate damping spring member engaging said manually operable actuator means at said second end and rigidly secured to said housing and positioned with respect to another end of said vibrator to coact with said vibrator at said other end in a first nonoperating position of said manually operable means and to move away from said other end when said actuator is slideably operated.
 5. An ultrasonic transmitter comprising: a housing, support means, mounted on said housing, an elongated rod mounted on said support means and adapted to resonate within said ultrasonic band upon being mechanically excited, an actuator mechanism slideably mounted on said housing and having a first flanged end and a second end, a striking mechanism including a spring moveably mounted with respect to said housing and positioned at one end of said rod, said striking mechanism being coupled to said second end of said actuator mechanism to compress said spring when said actuator is caused to slide towards said striking mechanism, said compressed spring providing energy to cause a striking member to impinge upon said rod and therefore mechanically excite the same, a damping spring member of an arcuate shape and having a first end rigidly secured to said housing, said damping spring member coacting with said flanged end of said actuator member during a first position to cause said other end of said spring member to coact with the other end of said rod to restrain vibration and to move from said end to a second position, when said actuator slides towards said striking mechanism, to enable vibration.
 6. A manually powered ultrasonic signal transmitter comprising: a housing, a support member mounted on said housiNg, an elongated longitudinal mode mechanical vibrator having a predetermined natural ultrasonic frequency, means for mounting said vibrator on said support member, manually operable motion transmitting means mounted on said housing in a manner which provides for a sliding motion of the manually operable motion transmitting means, a striking element coupled to said motion transmitting means and responsive to the operation thereof to move against an end of said vibrator and to strike said vibrator to cause the same to mechanically vibrate at said predetermined frequency, and an arcuate spring damping element rigidly secured to said housing and coupled to said manually operable motion transmitting means, said arcuate spring member positioned to coact with another end of said vibrator to restrain vibrations when said manually operable means are not operated and to move away from said other end in response to a sliding motion of said manually operable means to permit vibrations. 